The present invention relates generally to heating and air conditioning systems, and more particularly relates to air conditioning systems that are particularly suited for large over-the-road vehicles.
As is known, large over-the-road vehicles such as tractor-trailer trucks are used for transporting a wide variety of items. Often, the transport routes of these vehicles are extremely long, frequently extending cross-county. On such long routes, the drivers of these vehicles frequently sleep within the vehicle. Accordingly, as is known, the passenger area of a large tractor-trailer truck is typically divided into a cab area and a sleeping area or bunk area (also known as the xe2x80x9csleeperxe2x80x9d). The bunk area is provided behind the cab area. Frequently, the bunk area is separated from the cab area by a curtain or other divider, and includes a bed upon which the driver can sleep.
It can certainly be appreciated that on hot summer nights or cold winter nights, the driver will operate the air conditioning system or heating system, at least in the bunk area to maintain a comfortable sleeping climate. Presently, this is done in many different ways. First, the driver may leave the truck running on idle to maintain power to the heating and air conditioning system, so that the appropriate temperature in the bunk area may be maintained. Since the drivers typically sleep for several hours at a time, this approach is undesirable in that it wastes fuel and places undue wear on the engine components that are left running. Furthermore, the constant engine noise is distracting, not to mention the release of carbon monoxide and other pollutants into the environment.
Another approach taken by drivers is often to superheat or supercool the bunk area, just before shutting the engine down. In this regard, the driver may direct the heating and air conditioning system to the bunk area and either overheat the area in the wintertime or cool it to an extremely low temperature in the summer time. Since the truck body provides some insulating characteristics, it takes a certain amount of time for the indoor and outdoor temperature to equalize. By superheating of supercooling the bunk area, (i.e., increasing the temperature differential), the driver can extend the time period before the temperatures have equalized. In mild climate areas, this approach may be sufficient. However, in extremely harsh climates, this approach does not provide a sufficient time period of comfortable climate and therefore the driver must restart the engine if he wishes to maintain a comfortable climate. Moreover, this approach tends to result in an uncomfortably hot or cold climate immediately after the driver shuts off the engine (i.e., the superheated or supercooled climate).
Another method for heating and cooling the bunk area is to use a heating and air conditioning system which is auxiliary in nature, in that it is capable of operating when the engine of the truck is shut off.
For example, proposals have been made for heating and air conditioning the bunk area which involve what is known as xe2x80x9cpassivexe2x80x9d auxiliary systems in that they use thermal storage media to store thermal energy during normal operation of the truck. Passive auxiliary systems then deliver that thermal energy in the form of heating or air conditioning when the engine of the truck is shut down, such as that disclosed in Peiffer et al., U.S. Pat. No. 5,901,572, the entire disclosure of which is hereby incorporated by reference. Passive systems require sufficient energy to be stored during normal operation of the truck to provide heating or air conditioning when the engine is shut down. Thus, these types of systems can only heat or cool the passenger area for a limited period of time. The amount of time that these passive systems can provide heating or cooling is limited by the size of the system and amount thermal storage media contained in the system. Further, in order to heat or cool the sleeper area for a prolonged time period, the thermal storage media must be charged by the operation of the truck for a prolonged period. Thus, the amount of heating or cooling available at any given time is also limited by how long the truck was previously operated.
In contrast to passive systems, heating and air conditioning systems which are xe2x80x9cactivexe2x80x9d are those systems which are connected to their own independent power source and do not rely upon storage media, such as that disclosed in Zeigler et al., U.S. Pat. No. 5,901,780, the entire disclosure of which is hereby incorporated by reference. Thus, these systems can drive the heating and air conditioning system for as long as is needed assuming that the independent power supply is sufficient. There are two proposed ways to power active heating and air conditioning systems. Fuel fired heating and air conditioning systems are known such as that disclosed in the ""780 patent. A more common form of an active heating and air conditioning system is an electrically powered system in which stored electrical energy (e.g. from a battery) is used to generate heat or cool the air. With either type of system, the size of the auxiliarly system can be matched to meet the particular heating or cooling requirements of the vehicle. Under existing technology, it is not uncommon for active system up require up to about 3500 BTU/hr of energy to adequately cool the bunk, area, and up to 7000 BTU/hr to adequately heat the bunk area.
While it is easy enough to simply bulk up or increase the size of an environmental control system to provide a desired total energy output whether it be a passive or active system, providing for such high energy outputs requires space, and is both inefficient and expensive. Specifically, larger heat or cooling outputs requires more thermal storage media for passive systems, or larger heaters and air conditioning compressors (or other air conditioning units) for active systems. Further, in over-the-road vehicles where space is very limited and vehicle designers like to allocate as little space as necessary for a particular system, increasing the size of an auxiliary environmental control system is not only expensive but also undesirable as it consumes valuable space. Prior art attempts at reducing size and cost of the most common systems (electrical systems) have primarily dealt with providing alternative systems such as passive systems.
Due to the power requirements and drawbacks and size of auxiliary environmental control units, such auxiliary systems have not been widely implemented. Instead, the most common practice still is to run the vehicle while the driver rests or super cool or superheat the bunk area.
In light of the above, it is a general aim of the present invention to provide a more efficient or practical way to heat and cool a sleeping area.
It is an objective according to one aspect of the present invention to provide a more efficient way to heat and/or cool the sleeping area of a vehicle that utilizes an auxiliary environmental control unit.
In that regard, it is an objective of the present invention to provide a more efficient way to heat and/or cool the sleeping area of a vehicle for both active and passive type environmental control units.
It is a further objective of the present invention according to a further aspect to reduce the size and cost of auxiliary heating and/or air conditioning units in over-the-road vehicles.
In accordance with these and other objectives, the present invention is directed an environmentally controlled sleeping area in which a thermal barrier projects above a bed to at least partially enclose all four sides of the bed. An environmental control unit providing thermally conditioned air between the four sides of the bed. The thermal barrier prevents thermally conditioned air from escaping to the surrounding area.
According to a significant aspect of the present invention, the invention is employed in the bunk area of a vehicle in which the bunk area is adjacent to a cab area of the vehicle. As is conventional, the bunk area has an end wall and a pair of side walls extending generally perpendicular to the end wall. The side walls and the end wall encompass or surround three sides of the bed. Along the remaining open side of the bed, the vehicle operator can maneuver in and out of the bed. An extendible and retractable thermal barrier is provided along the remaining open side of the bed. The thermal barrier rises above the top surface of the bed and thermally separates the sleeping area from a remainder of the bunk area. An environmental control unit provides thermally conditioned air between the back wall and thermal barrier that becomes trapped therebetween by virtue of the thermal barrier.